European Patent Application No. 0,005,129 concerns substituted pyridylsulfinylbenzimidazoles which are said to have properties of inhibiting secretion of gastric acid. The use of a number of benzimidazole derivatives for inhibiting secretion of gastric acid is referred to in European Patent Application No. 0,074,341. British Patent Application GB No. 2,082,580 involves tricyclic imidazole derivatives which are said to inhibit secretion of gastric acid and to prevent ulcer formation. In U.S. Pat. No. 4,472,409 and in U.S. applications Ser. No. 606,872 and Ser. No. 606,873 (both filed on May 1, 1984) trifluoromethyl compounds, fluoroalkoxy compounds and tricyclic ethers with benzimidazole structure and a marked protective effect on the stomach are described.